Story highlights

Argentina's president declared a two-day mourning period after a commuter train plowed into a barrier at a Buenos Aires station, killing 50 people and injuring hundreds more.

Rescuers pried open windows of twisted train cars after the accident Wednesday to reach trapped passengers as helicopters flew some victims to area hospitals.

"The government and people of Argentina give their solidarity and weigh the pain felt by the families of the victims," President Cristina Fernandez de Kirchner said in a statement declaring the mourning period. Memorials will be held outside Argentina's Government House and Olivos, the presidential residence, the state news agency Telam reported.

"Never in my life had I seen anything like this," Transportation Secretary Juan Pablo Schiavi told reporters hours after the accident, which occurred during the height of the morning rush.